Endocrine Glands and Associated Hormones that Influence the Menstrual and Ovarian Cycles

Hypothalamus Produces and releases Gonadotropin Releasing Hormone (GnRH) Stimulates the Anterior Pituitary Gland to produce and release Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

Anterior Pituitary Gland Produces and secretes FSH and LH FSH - stimulates the initial development of the ovarian follicles and secretion of estrogen by the follicles LH - stimulates further development of the ovarian follicles, brings about ovulation, and stimulates the production of estrogens, progesterone, inhibin, and relaxin by the ovarian cells of the corpus luteum

Ovaries Secrete the hormones Estrogen, Progesterone, Relaxin, and Inhibin Estrogens At least 6 different types Development and maintenance of the female reproductive system Helps control fluid and electrolyte balance Increases protein anabolism

Progesterone - hormone of maturation Works in conjunction with estrogen to prepare the endometrial lining for implantation of a fertilized ovum Stimulates milk production and secretion Inhibin - secreted by the corpus luteum Inhibits secretion of FSH and LH Relaxin - produced by the corpus luteum during pregnancy Most prominent during the final trimester of pregnancy Relaxes the pubic symphysis and helps dilate the cervix to facilitate delivery

Menstruation (The Menstrual Phase) The periodic discharge of 50 to 150 ml of blood, tissue fluid, mucus, and epithelial cells Caused by the sudden reduction of estrogens and progesterone Lasts approximately the first 5 days of the menstrual cycle Results in the shedding of the stratum functionalis layer of the endometrium The 1st day of the ovarian cycle is designated by the 1st day menstruation

Preovulatory Phase or Proliferative Phase The time between menstruation and ovulation Variable in length Usually from day 6 to day 13 in a 28 day cycle Characterized by repair and build up of the endometrium

Ovulation the rupture of the vesicular ovarian (Graafian) follicle and the release of the secondary oocyte into the pelvic cavity usually occurs on day 14 of a 28 day cycle fimbriae of the uterine tubes become active create currents to draw the secondary oocyte into the uterine tubes

Ovulation

Post Ovulatory (Secretory Phase) The period of time after ovulation before the beginning of menstruation The most constant time in duration Usually lasts from day 15 to day 28 in a 28 day cycle Uterine lining is optimally developed to allow a fertilized egg to be implanted If implantation occurs, the developing placenta releases Human Chorionic Gonadotropin (HCG)

Menopause Characterized by the climacteric a situation where menstrual cycles become less frequent Typically begins between 40 - 50 years of age Caused by the ovaries failure to respond to FSH and LH

Physiological Changes with Menopause Atrophy of the ovaries, uterine tubes, uterus, vagina, external genitalia and the breasts Increased risk for development of osteoporosis Increased risk for cardiovascular diseases

Symptoms of Menopause hot flashes muscular pains insomnia weight gain headaches hair loss vaginal dryness depression emotional instability copious sweating

Female Hormones Estrogens – produced by the ovaries and help to mature females as well as begin to prepare the lining of the uterus for a fertilized egg. Progesterone – produced by the ovaries and help to thicken and increase the blood supply to the endometrium.

Female Hormones Relaxin – produced by the ovaries and helps to relax the symphysis pubis during the later half of pregnancy in preparation for delivery of the fetus at the end of 40 weeks.